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Σημείο Fermi
Σημείον Fermi Fermi point thumb|300px| [[Φυσική Σταθερά Φυσική Σταθερά Μαθηματική Σταθερά ---- Φυσικές Σταθερές Μαθηματικές Σταθερές ---- Φυσικό Μέγεθος Μαθηματικό Μέγεθος ---- Μονάδα Μέτρησης Αριθμός ]] - Ένα φυσικό "σημείο" Ετυμολογία Η ονομασία "Σημείο Fermi" σχετίζεται ετυμολογικά με το όνομα "Fermi". Εισαγωγή The fermi point is an amount of energy. Unless excited fermions, will fill every state available that have energy less than or equal to the fermi point. Usually the Fermi level is used to discuss electrons in semiconductors and metals. In semiconductors at absolute zero, electrons will fill up every available state that have energy of less than or equal to the fermi point. At higher temperatures, some electrons will be excited, so there will be some electrons with energies above the fermi level. Ανάλυση The term Fermi point has two applications but refers to the same phenomena (special relativity):Effective gravity and quantum field theory in superfluids *Fermi point (Quantum Field Theory) *Fermi point (Nanotechnology) For both applications count that the symmetry between particles and anti-particles in weak interactions is violated: At this point the particle energy E = cp is zero.Field theory in superfluid 3He: What are the lessons for particle physics, gravity, and high-temperature superconductivity? In nanotechnology this concept can be applied to electron behavior.METFET An electron when as single particle is a Fermion obeying the Pauli exclusion principle. Fermi point (Quantum Field Theory) Fermionic systems that have a Fermi surface (FS) belong to a universality class in quantum field theory. Any collection of fermions with weak repulsive interactions belongs to this class. At the fermi point, the break of symmetry can be explained by assuming a vortex or singularity will appear as a result of the spin of a fermi particle (quasiparticle, Fermion) in one dimension of the three-dimensional momentum space. Fermi point (Nanoscience) The Fermi point is one particular electron state. The Fermi point refers to an event chirality of electrons is involved and the diameter of a carbon nanotube for which the nanotube becomes metallic. As the structure of a carbon nanotube determines the energy levels that the carbon's electrons may occupy, the structure affects macroscopic properties of the nanotube structure, most notably electrical and thermal conductivity.Sundaram, Vivek. Dept. of Mechanical Engineering University of Colorado at Boulder. CARBON NANOTUBES: One of the best discoveries man has ever made in Science. Retrieved April 1, 2006. Flat graphite is a conductor except when rolled up into small cylinders. This circular structure inhibits the internal flow of electrons and the graphite becomes a semiconductor; a transition point forms between the valence band and conduction band. This point is called the Fermi point. If the diameter of the carbon nanotube is sufficiently great, the necessary transition phase disappears and the nanotube may be considered a conductor.Gross, Michael. chembytes e-zine. The smallest revolution. Retrieved April 1, 2006.Carbon Nanotubes and Nanotube Transistors. Chirality For a given (n'',''m) nanotube, if n'' - ''m=3''q'' (where q'' is an integer), then the nanotube is metallic, otherwise the nanotube is a semiconductor. Thus all armchair nanotubes (''n=''m'') are metallic, and nanotubes (5,0), (6,4), (9,1), etc. are semiconducting. Υποσημειώσεις Εσωτερική Αρθρογραφία * Κβαντική Πεδιακή Θεωρία * Fermi energy * Fermi surface * Bandgap Βιβλιογραφία * * Ιστογραφία *Ομώνυμο άρθρο στην Βικιπαίδεια *Ομώνυμο άρθρο στην Livepedia *[ ] *[ ] Κατηγορία:Φυσικά Σημεία